This invention relates to a time correction circuit for an electronic timepiece, and more particularly to an electric circuit for correcting the time and date of an electronic timepiece.
With recent advance in the art of large scale integrated circuits (LSI) conventional mechanical timepieces are now gradually changing to electronic timepieces. Electronic timepieces are classified into a register type and a frequency division type and both types involve the problem of time correction. A number of methods have been proposed for effecting time correction. According to one method a mechanical switch is closed and opened to generate an electric signal which is applied to an electronic circuit for producing a digital signal which is applied directly or indirectly to a closed loop circuit or a frequency division circuit constituted by transistors or the like for correcting the hour, minute, second and date displays. In the mechanical switch the chattering interval of the switch occurring at the time of operation varies depending upon the mechanism and material of the switch. The switch in which the chattering interval is limited to be less than 30 milliseconds is expensive whereas the accuracy of the electronic timepiece wherein the chattering interval of the switch exceeds 30 milliseconds is low. For this reason, the chattering interval is generally set to be about 30 milliseconds.
Where a mechanical switch is used to correct the time, the switch is maintained in the closed state for a predetermined interval for producing a continuous electric pulse or operated intermittently for intermittently producing an electric pulse for effecting the time correction. When correcting the date or time, the method wherein the switch is maintained closed for a relatively long period can not correct small error whereas with the method wherein the switch is operated intermittently, it is necessary to depress the switch many times where the error is large.